On Sun, 4 Jun 2006, Federico Giannici wrote:
> I have just switched to a multiprocessing kernel (3.9-stable i386) with a dual
> core Athlon 64.
>
> I noticed that "top" command now have two "CPUx" rows, one for each CPU. But
> "iostat" has only one "cpu" column.
>
> Question 1: are the iostat's cpu values a mean of the values of both CPUs?
More or less.
>
> Regarding the "load average", obviously, even with two CPUs, there is only one
> value. The problem is that it seems that it's values are almost the same of
> the uniprocessor kernel.
>
> Question 2: given that with with double CPUs there is half the probability to
> find a busy CPU, shouldn't the load averages be about the half of the previous
> values?
Why? The load avarage is defined as being the average length or the run
queue, i.e. the number of processes requesting CPU time averaged over
a certain amount of time.
If there are two processes requesting CPU all the time, the load
average will be about 2. The number of processors has no influence on that.
-Otto
